This invention relates generally to radiation stabilized fabrics and more particularly concerns polypropylene nonwoven fabrics that are stabilized against ionizing gamma radiation.
Disposable surgical fabrics for masks, gowns, drapes, towels, and the like are sterilized during manufacture by sealing such surgical products in plastic containers and subjecting the containers to ionizing radiation. During storage the surgical products within the sealed packs retain their sterile condition and are ready to use when the pack is opened.
Because such products are intended to be used once and discarded, the fabrics must be sufficiently low in cost to justify disposal as compared to woven fabrics which can be washed, sterilized, and reused. In producing low cost nonwoven surgical products, polypropylene based fabrics have found wide acceptance because of their advantageous features and cost. A typical example of a surgical fabric is the fabric used in SPUNGUARD.RTM. health care products sold by Kimberly-Clark Corporation, the assignee of the present invention. The fabric used in the SPUNGUARD health care products is a three layer laminate of spun-bonded polypropylene, melt-brown polypropylene, and spun-bonded polypropylene forming a fabric having a basis weight of 1.4 ounces per yard square (oz/yd.sup.2). Such a fabric has superior technical properties such as bacterial filtration, lint, and strength compared to other nonwoven products.
In order for surgical fabrics to be acceptable in an operating room environment, it is necessary that the fabrics be treated to assure electrical conductivity so that static electricity cannot build up on the surface of the fabrics and produce a spark in the environment of the operating room. Surgical fabrics should also be alcohol repellent. It is also important that surgical fabrics retain a significantly long shelf life to insure that upon removal from a hospital stockroom, the surgical fabric retains all of those advantageous characteristics that it had when it was first manufactured. Finally, it is necessary that the surgical fabric be sterilizable by treatment with gamma radiation without losing its other advantageous features such as its conductivity, strength, and repellency.